Mazda made a game-changing fuel efficiency breakthrough other carmakers have spent decades working on

A TV cameraman films during a news conference for the launch of the remodelled Mazda3 compact car in Tokyo June 11, 2009. REUTERS/Michael Caronna As soon as 2019, Mazda will have a petrol-driven car in production that is cheaper to run than a Tesla Model S.

The Japanese carmaker has announced it is ready to reveal a combustion engine using compression technology Ford, General Motors and Hyundai have been trying to get into production for the best part of a decade.

It's called Spark Controlled Compression Ignition and it uses the same sparkless technology used by diesel engines, without the high emission rate.

At low revs, the SkyActiv-X employs sparkplugs to ignite petrol, but it switches to compression ignition at high revs. Mazda claims it can handle the switch without engine damage.

If its claims of a "20-30%" increase in fuel efficiency are true, then the 2019 Mazda3 - the model most likely to get the first SkyActiv-X engine - could be running on as little as 3.5L per 100km.

At today's fuel prices in Melbourne, that's $19.25 for 500km, which is about the maximum range of a full battery in Tesla's Model S.

That is a problem electric carmakers have to start getting concerned about, at least in Australia. As much as Tesla and other EV manufacturers would like to think their products are desirable for their green credentials, being cheap to run is undeniably a major sell point.

Tesla

And right now, in Australia, if you had to make a savings call based on rising fuel prices versus rising electricity costs…

Of course, a Mazda3 can't rush from 0-100km/h in under 3 seconds, or be summoned from a carpark. But you could also buy five of them fully loaded for the price of a mid-range Tesla Model S.

Or one and have at least another $30,000 in your hand for the price of Tesla's new, much slower, Model 3. That's enough to buy you 780,000km worth of petrol.

You also have to consider that with less than 6% of Australia's energy sourced from renewables, the likelihood is high that your Tesla is still getting its Aussie energy from burning carbon.

On the emissions side of things, the new Mazda3 could be pumping out less than 95g/km, in line with European requirements by 2020. While there are early plans in Britain, France, the Netherlands and Germany to ban all combustion fossil fuel-powered engines by 2040, Mazda is clearly determined to make a case for low-emission technology.

But it's also pushing on with its electric models. At yesterday's announcement, it said it would continue to develop cars for "regions that use a high ratio of clean energy for power generation or restrict certain vehicles to reduce air pollution".

A new SkyActiv-X Mazda6 is expected to follow soon after the 3 launch.